1. Field of the Invention
The present invention relates to a technology for generating a pulse modulation signal for driving a light source.
2. Description of the Related Art
Optical scanning devices are widely used in image forming apparatuses such as optical printers, digital copiers, and optical plotters. A typical optical scanning device scans a target surface with light modulated according to image data. By this scanning, a latent image corresponding to the image data is formed on the target surface.
The optical scanning device typically drives a light source by using a modulation signal of which pulse is modulated according to image data so that the light source emits light that is modulated according to image data. Examples of such an optical scanning device are disclosed in Japanese Patent No. 3515087 and Japanese Patent No. 3372564.
Reduction in power consumption of image forming apparatuses has been increasingly demanded in recent years. In response to these demands, a reduction in power consumption of optical scanning devices has been attempted. However, a pulse-modulation signal generating circuit disclosed in Japanese Patent No. 3515087 and a signal generation device disclosed in Japanese Patent No. 3372564 are disadvantageous in terms of power consumption. More specifically, in the conventional techniques, because a larger number of light emitting units is required in a light source or a larger number of bit count and data lines is required to form an image at a higher resolution, power consumption can increase. It is also conceivable that even an additional cooling mechanism is required.